package controller

import (
	"errors"
	"strings"
	"time"

	"github.com/QuantumNous/new-api/common"
	"github.com/QuantumNous/new-api/model"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

type validatePromoCodeRequest struct {
	Code   string `json:"code"`
	Amount int    `json:"amount"`
}

type validatePromoCodeResponse struct {
	Valid       bool   `json:"valid"`
	Reason      string `json:"reason"`
	PromoCodeId int    `json:"promo_code_id"`
	BonusAmount int    `json:"bonus_amount"`
	Code        string `json:"code"`
}

func ValidatePromoCode(c *gin.Context) {
	var req validatePromoCodeRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		common.ApiError(c, err)
		return
	}

	code := normalizeUserPromoCode(req.Code)
	if code == "" {
		common.ApiErrorMsg(c, "优惠码不能为空")
		return
	}

	promoCode, err := model.GetPromoCodeByCode(code)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			common.ApiSuccess(c, newInvalidPromoCodeResponse(code, "not_found"))
			return
		}
		common.ApiError(c, err)
		return
	}

	if promoCode.Status != 1 {
		common.ApiSuccess(c, newInvalidPromoCodeResponse(code, "disabled"))
		return
	}
	if promoCode.ExpiresAt != nil && promoCode.ExpiresAt.Before(time.Now()) {
		common.ApiSuccess(c, newInvalidPromoCodeResponse(code, "expired"))
		return
	}
	if promoCode.MaxUses > 0 && promoCode.UsedCount >= promoCode.MaxUses {
		common.ApiSuccess(c, newInvalidPromoCodeResponse(code, "max_uses_reached"))
		return
	}
	if req.Amount < promoCode.MinRechargeAmount {
		common.ApiSuccess(c, newInvalidPromoCodeResponse(code, "below_min_recharge"))
		return
	}

	userId := c.GetInt("id")
	if _, err := model.GetPromoCodeUsageByCodeAndUser(promoCode.Id, userId); err == nil {
		common.ApiSuccess(c, newInvalidPromoCodeResponse(code, "already_used"))
		return
	} else if !errors.Is(err, gorm.ErrRecordNotFound) {
		common.ApiError(c, err)
		return
	}

	common.ApiSuccess(c, validatePromoCodeResponse{
		Valid:       true,
		Reason:      "",
		PromoCodeId: promoCode.Id,
		BonusAmount: promoCode.BonusAmount,
		Code:        promoCode.Code,
	})
}

func normalizeUserPromoCode(code string) string {
	return strings.ToUpper(strings.TrimSpace(code))
}

func newInvalidPromoCodeResponse(code string, reason string) validatePromoCodeResponse {
	return validatePromoCodeResponse{
		Valid:  false,
		Reason: reason,
		Code:   code,
	}
}